The present invention relates to a two-dimensional nuclear magnetic resonance spectrometry and, more particularly, to a two-dimensional nuclear magnetic resonance spectrometry that can offer two-dimensional spectra whose phases have been corrected.
In recent years, two-dimensional nuclear magnetic resonance spectrometry has attracted special interest as a new NMR spectrometry. According to this spectrometry (the spectrometry specified by W. P. Aue, E. Bartholdi, and R. R. Ernst in "Two-dimensional spectroscopy. Application to nuclear magnetic resonance," Journal of Chemical Physics, Vol. 64, No. 5, Mar. 1, 1976, pp. 2229-2246), NMR signals are represented as a two-dimensional spectrum, and therefore it yields higher resolution than the prior art method, i.e., a resonance line is better split into multiplet lines. This facilitates analyzing spectra and so the spectrometry is expected to find much wider application in the future.
FIG. 1 shows a sequence of measurements made for J-resolved two-dimensional NMR which is one of the two-dimensional NMRs. Specifically, a 90.degree. pulse and a 180.degree. pulse are applied at a time interval of t.sub.1 /2 to a sample containing gyromagnetic resonators. After the lapse of t.sub.1 /2, the resulting free induction decay signal is detected for a period t.sub.2 and stored in a memory. This one measurement is repeated many times with incrementally different values of t.sub.1. The free induction decay signals which are obtained by these measurements are stored in the memory, corresponding to the values of t.sub.1. Then, the set S(t.sub.1, t.sub.2) of the signals are subjected to double Fourier transformation with respect to t.sub.2 and t.sub.1 to derive a two-dimensional spectrum.
In this two-dimensional NMR spectrometry, it is difficult to correct the phase of the obtained two-dimensional spectrum. Therefore, the spectrum is derived as a power spectrum that is independent of phase. In a power spectrum, any peak terminates in a tail. Near such a tail resonance lines cannot be well separated. In an attempt to maximize the separation free induction decay signals have been heretofore multiplied by various window functions. However, complete separation has been impossible to realize. Further, the multiplications using window functions pose the additional problem that peaks vanish.